Automatic variable leverage mechanism



y 2, 1940- v s. SCHNELL 2,206,648

AUTOMATIC VARIABLE LEVERAGE MECHANISM Filed Dec. 16, 1958 INVENTOR:

E SCHNELL ,B g /W ATTORNEY Patented July 2, 1940 UNITED STATES PATENT OFFICE AUTOMATIC VARIABLE LEVERAGE MECHANISM tion of Delaware Application December 16, 1938, Serial No. 246,076

8 Claims.

My invention relates to levers and more particularly to lever mechanisms which permit the leverage ratio to be automatically changed.

One of the objects of my invention is to pro- 6 duce an improved lever mechanism of the type referred to which will actuate a member by one leverage ratio and then when the force necessary to actuate said member becomesgreater than a predetermined value. the leverage ratio will be automatically changed.

Another and more specific object of my invention is to produce a leverage mechanism whereby a member may be operated by a lever hrough one connection and at a given leverage ratio and when the force necessary to actuate the member becomes a predetermined value, said connection will become inoperative and the lever will then operate the member through a second connection and at a higher leverage ratio.

29 Still another object of my invention is to provide a lever mechanism of the type above referred to with manually-controlled detent means for holding the mechanism in any of its operative positions and for also permitting the mechanism 25 to be released and returned to its inoperative position whenever the main control lever is returned to its inoperative position.

Otherobjects of my invention will become apparent from the following description taken in connection with the accompanying drawing in which Figure l is a sideview of a lever mechanism embodying my invention; Figures 2 and 3 are cross-sectional views taken on the lines 2-2 and 35 3-3, respectively, of Figure 1 and showing details of construction.

Referring to the drawing'in detail, numeral i indicates a main hand lever having an upper hollow portion 2 and a bifurcated lower portion pro- 40 viding arms 3 and 4. The lever is pivoted at its intermediate portion to a support 5 by means of a pin 6. A fixed plate 1 of irregular shape is -also' mounted on the support by means of the pivot pin 6 and a bolt 8, the portion which cooperates with the pin 6 extending between the arms 3 and 4. The lower portion of the plate extends adjacent the lower ends of the arms and the edge thereof is provided with teeth 9 and a shoulder l0.

Also pivotally mounted on pin 6 within the arms 50 3 and 4 and on opposite sides of plate 1 are two arms H and I2 of like construction. These arms are of such length as to extend to the lower edge of plate I andthe end edges thereof are provided with teeth I3.

The member to be operated by the lever is shown as a shaft 14 which may be suitably connected to any other device which it is desired to control. An arm IS, in the form of a plate, is secured to the shaft and the shaft also rotata-bly 5 carries two similar arms l6 and I1 positioned on opposite sides of plate IS. The lower ends of these arms extend below the plate and pivotally mounted thereon is a detent l8 having at one end a shoulder IQ for cooperation with a shoulder 10 on plate I5, said shoulder being normally held in engagement by a spring 2|. The other end of the detent is pivotally connected to a pair of links 22 and 23 which are pivotally connected to the lower end of arms 3 and 4 of the main lever I. The pivotal connection between the. detent and the'links is such, in relation to the pivot of the detent, that when force is transmitted through the links to move plate IS, a component of force will be present which tends to cause shoulder I9 20 to become disengaged from shoulder 20 against the bias of spring 2|. A pair of links 24 and 25 are also provided to connect the lower end of plate IS with the intermediate portions of arms H and I2.

The pin 26 which connects the links 22 and 23 to the lower ends of arms 3 and 4 carries two similar pawls 21 and 28 for cooperation with teeth l3 on the lower ends of the arms II and I2. The free ends of the pawls are secured together by means of a toothed member 29 interposed between and welded to the pawls. This toothed member lies in the same 'plane as plate 1 and cooperates with shoulder ID to. disengage the pawls from teeth l3 when the lever is released. A spring 30 biases the pawls toward engagement with the teeth. Also pivotally mounted on pin 26 is a pawl 3| extending in the opposite direction to pawls 21 and 2B and adapted to cooperate with the teeth '9 on plate I. This pawl is controlled by a rod 32 which extends upwardly through the hollow portion 2 of lever I and carries a button 33 whereby the pawl can be disengaged by the' thumb of the operator. when his hand is gripping the upper end of the lever. A spring 34 biases the rod to a position where pawl 3| will automatically engage with the teeth 3 when the lever is moved. In order to form a stop for determining the "off position of lever l, the arms II and I2 carry a pin 35 which engages the forward end 0! a slot 36 in plate I.

Referring to the operation of the lever mechanism just described, when it is desired to rotate shaft l4, lever l is grasped by the hand of the operator and moved in the direction of the arrow. With the parts in the ofl position, as shown, the first movement of the lever results in force being transmitted through links 22 and 23 and pawl I8, thereby rotating plate I 5 and the shaft. Rotation of plate I5 will cause links 24 and 25 to swing arms II andl2 in a clockwise direction and at a greater rate than the lower arms 3 and l of the lever due to the fact that links 24 and 25 are connected to arms II and I2 at a point closer to pivot 8. Initial movement of lever I also causes the toothed member 29 on the pawls to ride down shoulder I0 and permit the pawls to be in a coopcrati g position'with respect to teeth I3, the

teeth, however, ratcheting past the pawls due to,

the more rapid movement of arms II and I2 than the lower end of the lever.

When the force being transmitted through links 22 and 23 becomes of such value that the component thereof tending to disengage the detent I8 is sufficient to overcome the bias of spring 2|, the shoulders I 9 and 20 will'be forced out of engagement and the connection between the links and the plate will be broken. Since the pawls 21 and 28 are already in position to cooperate with teeth I3 these pawls will pick up a tooth and cause arms II and I2 to move as a unitwith the lower end of lever I. Force will now be transmitted through links 24 and 25 to plate I5, thereby continuing the rotation of this plate and the shaft but at a higher leverage ratio since links 24 and 25 are connected to arms II and I2 at a point closer to the axis of lever I. The movement of lever I brings pawl 3i into position for cooperation with teeth 9, thus causing lever I to be held in any operative position desired when the lever has been moved the desired distance.

When it is desired to release the lever mechanism and return the parts to their ofi position, rod 32 is pushed downwardly, thereby disengaging pawl 3|. The lower end of lever l is now free to move in a counter-clockwise direction and when moved sufficiently in this direction to bring the toothed member 29 into engagement with shoulder I 0, pawls 21 and 28 will be positively moved to an inoperative position, thereby permitting arms II and I2 to move relatively to the lever and return totheir original positions. My improved lever mechanism has been found to be useful in operating numerous kinds of mechanisms, an example being the application of brakes. The first movement of lever I will cause the friction element of the brakes to be brought into engagement with the drum at the low leverage ratio which-is the desired operation. The change-over to the high leverage ratio will automatically take place as soon as the greater force is necessary to apply pressure to the friction element and force it into braking engagement with the drum. Regardless of the angle that shaft I4 or plate I5 must be rotated to bring the friction element into engagement with the drum, the change in leverage ratio will automatically take place at theproper time. It is thus seen that the wear of the friction element will have no effect in altering the time of the changeover.

Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles of my invention, I do not intend that its scope be limited except as set forth by the appended claims. I

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

. lever and the actuated member, a second connection between the pivoted arm and the actuated member, means for causing the first named connection to become inoperative and incapable of transmitting any force when the force transmitted therethrough by the lever to move the actuated member is greater than a predetermined value, said arm being moved by said second connection when the actuated member is moved by the first connection, and means for connecting the pivoted arm to the lever whereby when said first connection is caused to be inoperative the actuated member-will be operated through the arm and the second connection, said last named means comprising teeth on the end of the arm and a cooperating pawl pivotally carried by the lever.

2. In a lever mechanism, a member to be actuated, a pivotally mounted lever, a member pi'voted coaxially with the lever, means comprising an automatically operable disconnecting means for connecting the lever and the actuated member, said disconnecting means causing the connection to be inoperative when the force transmitted therethrough by the lever to move the actuated member is greater than a predetermined value, a connection between the pivoted member and the actuated membenmeans for connecting the pivoted member and the lever for unitary movement when said connecting means is caused to be inoperative whereby the actuated member will be operated through the connection between it and the pivoted member, and manually releasable means for holding the lever in any of a plurality of operative positions.

' 3. In a lever mechanism, a member to be actuated, a pivotally mounted lever, a member pivoted coaxially with the lever; means for connecting the lever and the actuated member and comprising a link pivotally connected at one end to the lever and a yieldable detent means connecting the other end of the link to the actuated member, said detent means being automatically moved to a disconnecting position where no force can be transferred through the link when the force transmitted therethrough by the lever to move the actuated member is greater than a predetermined value, .a second link connecting the pivoted member and the actuated member, and means for automatically connecting the pivoted member and the lever for unitary movement when the detent means assumes a disconnecting position.

4. In a levermechanism, a member to be actuated, a pivotally mounted lever, a member pivoted coaxially with the lever, means comprising a link and yieldable detent means for connecting the levera'nd the actuated member, said detent means being automatically moved to a disconnecting position when the force transmitted therethrough by the lever tomove the actuated member is greater than a predetermined value, a second link connecting the pivoted member and the actuated member, means for automatically connecting the pivoted member and the lever for 'unitary movement when the detent means asto be actuated, a second member pivoted coaxi-r tuated, a pivotally mounted lever, a member pivoted coaxlally with the lever, means comprising a link and yleldable detent means for connecting the lever and the actuated member, said detent means being automatically moved to a disconnecting position when the force transmitted therethrough by the lever to move the actuated member is greater than a predetermined value, a second link connecting the pivoted member and the actuated member, means ior automatically connecting the pivoted member and the lever for unitary movement when the detent means assumes a disconnecting position, a fixed plate provided with teeth, a pawl carried by the lever for cooperating with the teeth of the plate to hold the lever in any of a plurality of operative positions, and means carried by the lever for releasing the pawl.

6. In a lever mechanism, a shaft, an arm fixed to the shaft, a pivotally mounted lever spaced from the shaft, a connection between the lever and the arm including a yieldable detent, an arm pivoted coaxially with the lever, a second connection between the last named arm and the arm fixed to the shaft, means comprising a pawl carried by the lever for automatically connecting the lever to the coaxially pivoted arm when the force transmitted through the first connection is of such value as to cause the yieldable means to assume a disconnecting position, and manually releasable means for holding the lever in its operative position.

7. In a lever mechanism, a pivoted member ally therewith, a remote pivotally mounted lever, an arm pivoted coaxially with the lever, a detent pivoted on the second member and engaging the actuated member, a link connected to the lever and to the detent in such a manner that the detent will be disengaged from the actuated member when a predetermined force is transmitted through the link by the lever, a second link connecting the arm and the actuated member, and means for automatically connecting the arm to the lever for unitary movement when the detent is disengaged.

8. In a lever mechanism, a pivoted member to be actuated, a second member pivoted coaxially therewith, a remote pivotally mounted lever, an arm pivoted coaxially with the lever, a detent pivoted on the second member and engaging the actuated member, a link connected to the lever and to the detent in such a manner that the detent will be disengaged from the actuated'memher when a predetermined force is transmitted through the link by the lever, a second link connecting the arm and the actuated member, means comprising a pawl pivotally carried by the lever and cooperating teeth on the arm for automatically connecting the arm to the lever for unitary movement when the detent is disengaged, and means for positively disengaging the pawl from any tooth with which it may be engaged when t the lever assumes an inoperative position.

STEVE SCHNELL. 

